Device for recording and reproducing sound



v E.KRAMER DEVICE FOR RECORDING AND REPRODUCING SOUND Filed Ma; 3. 1

Patented Oct. 18, 1927.

PATENT OFFICE.

.nlRJNIN KRAMER, 0F BERLIN, GERMANY.

DEVICE FOR RECORDING AND REPRODUCING SOUND.

Application filed May 1, 1924, Serial No. 710,295, and in Germany May 3, 1923.

My invention relates to devices for recording and reproducing sounds and more particularly to devices of this kind with a tone arm and sound box to which motion is transmitted from the shaft that moves the record or impression carrier.

It is well known that for the production of sound impressions and the reproduction of the sounds directly from the record on which the sound impression was originally produced the exact guiding of the tone arm with the sound box and exact regulation of the feed motion of said arm is necessary.

The object of the present invention is to provide a device in which the feed motion always corresponds exactly to the impression lines on the record even if the driving shaft of the motor rotates the record disk that does not run quite true, as is often the case in commercial apparatus. This object I accomplish by coupling the device which trans-- mits the lateral feed motion to the tone arm and sound box, with the shaft-of the record in such a way that the feed motion participates in'the inaccuratemotions of the shaft when the latter does not run true. In other words, means are provided for converting the motion of the shaft into a motion of the sound box across the sound impression carrier so that all the qualities of the shaft mo tion are converted into corresponding qualities of the. sound box motion. Hence, when the shaft oscillates laterally these oscillations are also imparted *to thesound box.

The sound impression lines produced on thedisk, or impression carrier, then will deviate according] from a true spiral line but crossings of adacent sections of the spiral line or undesirable approximation of these sec tions are efiectually prevented.

The novel arrangement can be carriedout in a simple manner, if a tone arm which swings across the record disk about a verticalaxis is employed. An advantageous feature of the invention also resides in the fact that the screw spindle for thefeed motion of the sound box can be dispensed with and that the sound box can be shifted laterally to any desired position by hand by simply moving the sound box without previously releasing any motion transmitting members. The elimination of the screw spindle for the feed motion of the sound Fig. 2 is a vertical section through the central shaft along line 22 in Fig. 1 and Flg. 3 a side view of the tone arm and a vertical section through its pivot along line.

33 in Fig.1.

The table 1 that carries the record or impression carrier, 20 is rotated by the shaft 2. Arranged to move laterallyacross the record 20 is the tone arm 4 provided with a vertical piNot 3 journalled in a hinge 6 adapted to swing on a horizontal pivot 7 carried by uprights fixed to a plate 8. The plate 8- has another upright 9 which receives a set screw 10 against which the lower end of the hinge 6 abuts. By means of tile screw 10 the tone arm 4 with the sound box 5 can be swungup or down any distance so that the position of the sound box 5 can be made to correspond to the height of the record 20.

Attached to the front end of the tone arm 4 is an arm 11 to which is attached a rod 12 by a ball joint 13. Feed motion is trans ferred,to the tone arm 4 and the sound box 5 across the record 20 by means of the rod 12. Attached to the top end 14 of the shaft 2\ by means of a spring sleeve 15 is a bellshaped member 16 whose periphery bears against the record 20 so as to press it suflicient-ly firmly against the table 1 so that it is carried around by the latter. Attached to the bell-shaped member 16 by a screw 18 is. a cup-shaped member 17. The cup-shaped member 17 fits loosely on the'screw 18 so that the'bell-shaped member 16 may turn relatively to the member 17. On the top surface of the head of the screw 18 is formed a worm 19. This worm meshes with the teeth of a worm-wheel 21 adapted to rotate about a horizontal shaft 22. The shaft 22 is fixed in the cup 17 out of the center of the shaft 2 so that only the left part of the worm 19 meshes with the wheel 21. Fixed to the latter is a friction pulley 23 that engages the feed rod 12 which latter may be pulled downward if necessary by a spring 24 one end of which is attached to the tone arm. Mounted on the rim of the cup 17 is a roll that revolves on a vertical pivot and bears against the rod 12 so as to prevent the cup 17 from rotating beyond a certain position.

The aforedescribed device operates in the following manner: When the shaft 2 rotates, the member 15, 16 and the screw 18 provided with the Worm 19 revolve with it. The cup 17 is also carried round until the roll 25 strikes against the rod 12, which latter-is prevented from swinging in a'horizontal plane by the lateral flanges of the friction pulley 23. The cup 17 is thus prevented from turning with the member 15, 16. The rotating worm 19 meshing with the teeth of the worm wheel 21 rotates the lat ter about its shaft 22, at a slow rate of speed. With the latter rotates the friction pulley 23 imparting a very slow motion to the rod 12 so that the sound box 5 is positively moved across the impression carrier 20.

The sound box 5 can be moved to any desired point of the record 20 by hand and this one may do by seizing the handle 26,

thereby lifting the sound box slightly so that it does not scratch the record 20 and then shifting it into the desired position. The sound box may be shifted conveniently in this manner whilst the machine is running. The rod 12 simply slides over the friction pulley 23 when the sound box is thus shifted.

To cause the pulley 23 to grip the rod 12 securely, the pulley or the rod or both may be made of fiber, rubber or similar material, or they may be coated with such material. Also the friction pulley may be replaced by a sLnall toothed wheel and the rod 12 by a rac An advantage of the described mechanism is that because of the positive engagement between the various parts thereof, undesirable oscillations of the various parts are avoided and thus inaccuracies of the sound impression curves are prevented even tho the parts work loosely in each other and thereby lost motion arises. The apparatus can therefore be produced on a large scale since extremely. accurate methods of production are not required.

It will further be seen that even if the end 14 of the shaft 2 does not run true, the whole feed mechanism will oscillate to a corresponding extent so that the sound impression lines will run beside each other sufficiently accurately in spite of the untrue running of the shaft end 14.

When a record 20 is to be changed the tone arm 4 is swung back about the pivot 7 which gives free access to the table 1.

The sound box 5 'isshown diagrammatically. It is arranged in well known manner so that it can move independently of the tone arm 4. The horn or trumpet is attached to the upwardly extending mouth 27 of the tone arm 4.

The entire recording device can be removed from the apparatus by pulling the pivot 3 out of the hinge member 6. This is important when the recording device is to: be attached to existing sound reproducing machines. In such cases the adjusting device for adjusting the height of the sound box by means of the set screw 10 is particularly useful. This is not only a simple means of adjusting the height of the sound box but also enables the rod 12 to be placed in a sufiiciently horizontal position so as to ensure the proper engagement of the same with the friction pulley.

Instead of employing a tone arm that swings horizontally around a vertical axis a tone arm may be used which is shifted laterally in a parallel motion. The construction hereinbefore described is, however, conducive of great simplicity, easy manufacture and great adaptability of the talking machine. The same sound recording device may be employed for record carriers of different sizes if the tone arm is arranged in the form of a telescope so as to enable :it to be lengthened or shortened.

I claim 1. In a sound recording and reproducing device, a rotatable shaft, a record carrier mounted on said shaft, a movable tone arm, a sound box provided on said tone arm, a vertical pivot pin carrying said tone arm, a. rod pivotally connected to said tone arm, a horizontal worm arranged to rotate with said shaft, a worm-wheel in mesh with said worm, a horizontal shaft carrying said worm-wheel and means secured to said worm-wheel adapted to engage said rod for moving the same lengthwise.

2. In a sound recording and reproducing device, a rotatable shaft, a record carrier mounted on said shaft, a movable tone arm, a sound-box provided on said tone-arm, a vertical pivot pin carrying said tone arm, a hinged member containing said pivot pin so as to permit said tone arm to be upwardly tilted, a rod pivotally connected to said tone arm, a horizontal worm arranged to rotate with said shaft, a worm-wheel in mesh with said worm, a horizontal shaft carrying said worm-wheel and means secured to said worm-wheel adapted to engage said rod for moving the same lengthwise.

3. In a sound recording and reproducing device, a rotatable shaft, a record carrier mounted on said shaft, a movable tone arm, a sound box provided on said tone arm, a vertical pivot pin carrying said tone arm, a rod pivotally connected with said tone arm, a worm arranged to rotate with said shaft, a worm-wheel in mesh with said worm, means on said worm-wheel adapted to engage said rod for moving the same lengthwise, a rotatable cup-shaped member rotatably supporting said Worm-wheel, and means on said cup-shaped member adapted to bear on said rod for preventing the rotation of said cup-shaped member.

4. In a sound recording and reproducing device, a record carrier, a rotatable shaft, supporting said carrier, a movable tone arm, a sound box provided on said tone arm, a lengthwise movable rod linked to said tone arm, a Worm arranged torotate with said shaft, means rotatably connecting said worm with said shaft, a member loosely supported by said means, a Worm-wheel carried by said member in mesh with said worm, a friction disk carried by saidWorm-Wheel so as to engage the said rod, and an abutment on said member adapted to bear against said rod thereby preventing rotation of said member.

In testimony whereof I afiix my signature.

ERWIN KRAMER. 

